Re: [ST] for Marc -

>From: Matthew Heyer
>At full lean, the traction starts to give, the racer
>with his knee already on the ground I assume exerts
>to hold up the bike, traction is regained, and the
>racer continues on (with assumed dirty underwear -
I've heard about that, I had another picture with
knee pushing in my mind at first but I know what you
mean now. I wonder about the dynamics of such a (scary)
moment, I mean you can't hold up the full weight of the
bike with the sideway pushing of your upper leg alone,
right? So I'm guessing the front wheel has not fully lost
"traction" yet, but is sliding out (like the rear wheel
steering thing a bit) momentarily, with a corrective
push of the knee to get more weight on the tire. Except
that there's a flaw in that theory since you can't "push"
against anything in that position with that leg. I mean
you can push the knee sideways against the asphalt, but
since it is a force applied in the horizontal plane (well,
sort of horizontal), a yaw reaction of the rider is the
result. And since the outer (other) leg isn't tied to the
bike, the lower body of the rider (theoretically, if he
would be able to keep so much strain on his leg muscles)
would yaw outward of the turn. There's nothing really that
can control the bike from his lower body in that position,
so corrective knee pushing sounds very improbable to me.
Perhaps (and more logical I think) it's more like an
"oh f###" moment with the rider realizing he's sitting
more on his knee than on his saddle (because the bike is
sliding outward), almost instantly followed by a regain
of traction. This regain could be the result of the sudden
outward shift of net center of mass, since the rider is
basically ejected for a very brief moment. With traction
in place the rider was placing the net CoM inward of
the turn for ground play, with him sitting on his knee
there's only the CoM of the bike left which is more
outward of the turn, resulting in a sudden upright of
the bike because of centrifugal force. That makes much
more sense then the "pushing because he felt it sliding"
theory, doesn't it?
I guess that stuff can be practiced with the rear wheel
steering bike of the California Superbike School (which
will be held in the Netherlands in July for the first
time :-)).
Emile
www.piloot.com
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